Bob's exam score was 2.17 standard deviations above the mean. the exam was taken by 200 students. assuming a normal distribution, how many scores were higher than bob's?

Assuming that it is a normal distribution, then at 2 standard deviation 97.7 % belongs to the distribution and at 3 standard deviation 99.9 % belongs to the group. so to calculate the percentage in 2.17 standard deviation.
(2 - 2.17) / ( 2 - 3) = ( 97.7 - x) / ( 97.7 - 99.9 )
solve for x, which represents the percentage in the 2.17 standard deviations
x = 98.07 %
100 - 98.07 = 1.93 % scores were higher than bob's